1. Field of the Invention
The present invention relates to a portable terminal, and more particularly to a portable terminal wherein an external device is connected to the portable terminal to allow a user to more conveniently extend functions of the terminal, and includes an interface unit for controlling the external device.
2. Description of the Related Art
Recently, in line with the development of mobile communication technologies, portable terminals are widely used to receive mobile communication services. However, all terminals commercialized up to now incorporate the same operation pattern if they have the same model name. For example, if an incoming call is received, a terminal commonly blinks an LED (Light Emitting Diode) for a predetermined time while outputting a bell sound.
However, users are bored with the monotonous shape, function, and external functional components of the portable terminals. Thus, it is recently popular among portable terminal users to alter the configuration of the terminal for achieving their unique and creative shapes, functions, and external functional components.
Generally, users use an electrical sound signal of a speaker and a control signal of an LED as an input signal so as to alter the configuration of the terminals.
In terminals commercialized up to now, there is no way for users to modify peripheral device operations, pursuant to the specifications and fixed functions provided by manufacturers. Thus, in order to apply an additional LED or other optional functions to a model of the portable terminal currently on the market, it is necessary for users to disassemble the portable terminal and hardwire a lead line thereto.
FIG. 1A is a functional block diagram showing the conventional portable terminal.
Referring to FIG. 1A, the conventional portable terminal includes a modem CPU (Modulator and Demodulator Central Processing Unit) 10, a power supply unit 20, a device controller 30, a memory 40, and devices 50. Devices 50 may include more than one device. Here, explanations of a display unit, an LED and speaker controller, and a transmitter/receiver that are usually included in portable communication devices are omitted.
The device controller 30 controls the operation of the devices 50 based on a control signal that is generated from the modem CPU 10 by a control program stored in the memory 40. The modem CPU 10 and the device controller 30 are driven by electric power fed from the power supply unit 20.
The devices 50 refer to a predetermined number of fixed devices externally or internally mounted on a terminal currently on the market.
FIG. 1B is an exemplary view showing the structure of a pin for controlling the devices in the portable terminal of the prior art.
Referring to FIG. 1B, the modem CPU 10 outputs a predetermined number (n) of control signals (GPIO #1˜GPIO #n: General_Purpose-Input_Output #1˜General_Purpose-Input_Output #n) for controlling the predetermined number (n) of devices. Each of the control signals (GPIO #1˜GPIO #n) is used for controlling each of the devices mounted on the portable terminal such as an LED and a backlight.
Particularly, FIG. 1B illustrates, as an example, the structure for controlling the operation of an LED 51 by a control signal GIPO #1. Referring to FIG. 1B, the LED 51 is controlled by an npn transistor 31 and a resistor 33. Being operated by the control signal GPIO #1 outputted from the modem CPU 10, the transistor 31 applies a voltage Vcc to the LED 51. The resistor 33 adjusts the brightness of the LED 51. For example, in the case where the control signal GPIO #1 is set to have a signal level ‘h’ at a time when the portable terminal receives an incoming call signal, the control signal GPIO #1 enables the transistor to be activated when the portable terminal actually receives an incoming call signal. On the other hand, the LED 51 emits a relatively dim light when the resistor 33 has a higher resistance value, whereas the LED 51 emits a relatively bright light when the resistor 33 has a lower resistance value.
In order to add an LED to the portable terminal of the prior art, as mentioned above, it is necessary to disassemble the portable terminal, find an available signal line, and hardwire a lead line at a position of the signal line where the LED will be connected. For example, in order to add a separate LED that has the same operation characteristics as the LED 51, it is necessary to additionally connect a lead line between the LED 51 and the resistor 33 before adding the separate LED.
It is not easy for a general person, not skilled in handling electrical devices, to perform such a work. Even if a new LED has been added in such a manner, the newly added LED has the same operation properties as an inherent LED (for example, the LED 51 of FIG. 1A) that is originally mounted on the terminal. This is because there is no way to alter a program of controlling an LED of the terminal.
As mentioned above, in the prior art, there is no way for users to easily alter the configuration of the portable terminal. Further, even if the configuration of the terminal has been altered, there is no method to alter its function in various ways.